Pontiac Repair: Front end/suspension question..., power steering pump, buick lesabre

Question
Mr. Hagan,
I've got a 2001 Buick LeSabre (and I know you're listed under "Chevrolet", but it's a general question and I hope you can help).
I noticed a bad "shimmy" in the front end, so I had a couple of bad tires replaced (new ones installed on the front), all four tires balanced, and the alignment done.  But it still has the shimmy...mostly around 50-55 mph...then it goes away if I drive much faster.  (70 on in interstate, for example.)
During the alignment, the mechanic told me I had a leak in the power steering pump.  Could that cause the front-end "shimmy", or would it most likely be something else?
Any suggestions, advice you can offer are greatly appreciate.
Warm regards, and Happy Holidays!
David Gardner

Answer
I have had one lesabre that had a bad steering gear, no leaks but it did cause a shimmy, much worse when it was wet out.  But it sounds like you may have either a bent wheel or yet a bad tire.  A load force balance of the tire would tell you if the tire is bad.  I install a lot of tires and just cause they are new does not mean they are perfectly round.  If you can have the installer of the tires load force balance them or at least rotate them front to rear to see if the condition improves